By Nathan Seppa, Science News
PHILADELPHIA — Using basic written instructions and a standard testing kit, people can self-administer an HIV test with a degree of accuracy equal to what health-care workers achieve, according to a new study presented October 31 at a meeting of the Infectious Diseases Society of America.
Researchers at Johns Hopkins University in Baltimore offered people in the emergency room of an urban hospital the option of testing themselves for HIV while they were waiting. The 402 people who agreed to do a test were given a self-explanatory test kit that required either a pin-prick or a mouth swab. The participant then put a blood or saliva sample into a tube, and in 20 minutes the kit rendered a verdict of positive or negative for HIV.
Separately, hospital officials replicated the test on each person. The self-tests matched the hospital workers’ tests in 400 of the 402 cases, says Johns Hopkins clinical microbiologist Charlotte Gaydos. Overall, only two of the people tested positive for HIV, and in both of those two cases the self-test results matched the hospital results.
The kits, which detect antibodies against HIV, were the same ones health-care workers use in conducting routine HIV testing. Participants had no problems telling a positive result from a negative one, Gaydos says.
Past studies suggest that 2 to 13 percent of patients who seek medical care at emergency rooms are HIV-positive, making these venues excellent places to offer testing, Gaydos says. She was encouraged that more than 90 percent of people offered the test agreed to try it.
Early detection is paramount in the fight against HIV, says Michael Saag, an infectious disease physician at the University of Alabama at Birmingham. HIV is marked by a loss of immune cells called CD4 T cells, and catching the infection early allows doctors to intercede before an extreme drop occurs.
Normal CD4 cell counts range from 400 to 1,200 cells per cubic millimeter of blood. People with counts of less than 200 cells/mm(3) at the time they are first diagnosed with HIV have a 25 percent likelihood of dying within 10 years, whereas those with a count higher than 200 cells/mm(3) at first diagnosis have a 5 percent mortality risk over that time, Saag says.
“Early testing enables people to live a relatively normal life span,” Saag says. But getting a positive test on one’s own does raise potential risks. “It could be quite devastating for someone to get a positive test and not know what to do,” he says. Also, one domestic partner might coerce the other to undergo a test, he says.
“On the flip side, we’re dealing with a global pandemic [of HIV]. We need to take the gloves off and try to do everything we can,” Saag says.
Gaydos says that with further study, self-testing for HIV could get regulatory approval and become routine, just as pregnancy testing has become.